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Physiology & Medicine / How does Icariin, the PDE5-Inhibitor, compare with Viagra?
« on: 10/11/2016 14:36:24 »
Icariin is the only naturally-occurring compound that has been clinically shown to have PDE5 inhibiting effect. It is extracted from a plant called Epimedium (or horny goat weed), which is used in traditional Chinese medicine. Here's an excerpt from a clinical study:
Source: pubs.acs.org/doi/abs/10.1021/np800049y
I have seen many icariin/horny goat weed supplements with dosages up to 1000mg. Consumer feedback was generally around 50% positive, buy many of those may be no more than placebo effect. My question is - based on the data referenced above - how much icariin do you need to have an effect equivalent to 100mg of sildenafil citrate?
Quote
Plant extracts traditionally used for male impotence (Tribulus terrestris, Ferula hermonis, Epimedium brevicornum, Cinnamomum cassia), and the individual compounds cinnamaldehyde, ferutinin, and icariin, were screened against phosphodiesterase-5A1 (PDE5A1) activity. Human recombinant PDE5A1 was used as the enzyme source. Only E. brevicornum extract (80% inhibition at 50 μg/mL) and its active principle icariin (1) (IC50 5.9 μM) were active. To improve its inhibitory activity, 1 was subjected to various structural modifications. Thus, 3,7-bis(2-hydroxyethyl)icaritin (5), where both sugars in 1 were replaced with hydroxyethyl residues, potently inhibited PDE5A1 with an IC50 very close to that of sildenafil (IC50 75 vs 74 nM). Thus, 5 was 80 times more potent than 1, and its selectivity versus phosphodiesterase-6 (PDE6) and cyclic adenosine monophosphate-phosphodiesterase (cAMP-PDE) was much higher in comparison with sildenafil. The improved pharmacodynamic profile and lack of cytotoxicity on human fibroblasts make compound 5 a promising candidate for further development.
Source: pubs.acs.org/doi/abs/10.1021/np800049y
I have seen many icariin/horny goat weed supplements with dosages up to 1000mg. Consumer feedback was generally around 50% positive, buy many of those may be no more than placebo effect. My question is - based on the data referenced above - how much icariin do you need to have an effect equivalent to 100mg of sildenafil citrate?